<html>
<body>
<script src="ad_iframe_writer.js"></script>

<script>
  let adIframe = createAdIframe();
  let doc = adIframe.contentWindow.document;

  doc.open();
  doc.write("<html>Rewritten. <img src=pixel.png> <img src=pixel2.png> <img src=pixel3.png></html>");
  doc.close();
</script>
</body>
</html>
